The present invention relates to heating, ventilating and air conditioning (HVAC) systems for controlling environmental conditions in a room or space. More particularly, the present invention relates to an HVAC system vent structure, which is configured to provide a uniform velocity profile of exiting air.
In conventional building construction, HVAC ducts are formed of sheet metal and have rectangular cross sections. The ducts and outlet registers have cross sectional areas in the range of tens of square inches. Within conventional stud wall sections, the ducts often occupy most of the space between a pair of adjacent studs. Conventional home environmental systems move heated or cooled air at relatively low velocities.
In some newer ducting designs, cylindrical ducts are used which have much smaller cross sectional areas than more conventional ducts, in the range of less than ten square inches. Airflow through such smaller ducts is at a higher velocity than in conventional ducts to achieve comparable volumetric flow rates and to promote better mixing of conditioned air into the ambient air within a room. These smaller ducts typically have a lower manufacturing cost because less material is used, and because manufacturing labor is reduced. Additional advantages include more convenient installation and higher energy efficiency, because there is less surface area through which heat can be transferred.
A common problem with any vent structure is the generation of audible noise by air flowing through the vent structure and louvers. Airflow noise is generally caused by turbulence resulting from a change in the direction of air flow or a restriction that is too abrupt. Airflow noise can also result from structural components that are vibrated by the flow of air thereover, by natural resonances within the vent structure, and the like. Due to the higher flow velocities in the newer, smaller, cylindrical ducting designs, the potential for generating undesirable noise is increased.
To address this problem, Unico, Inc., assignee of U.S. Pat. No. 6,168,518 and assignee of the present application, developed a novel vent structure that connects between a small-diameter cylindrical airflow duct and a narrow rectangular outlet slot by way of a curved, angularly flared transition section that changes the direction of airflow and transitions from the circular cross section of the duct to the rectangular shape of the outlet slot with a minimum of turbulence and airflow noise. In developing the vent structure disclosed in U.S. Pat. No. 6,168,518, Unico determined that the cross sectional areas of the flared transition section and outlet section, in combination with the gradual curved shape of the flare section, minimized the introduction of turbulence in air flowing therethrough and, thereby, minimized the generation of airflow noise.
The present invention provides further improvements in such vent structures. One drawback to the newer, smaller-diameter, cylindrical ducting designs is that the high velocity flow through the ducts often causes air exiting an outlet vent or louver to be concentrated at a high velocity in a region of the outlet vent that is nearest to or aligned with the cylindrical ducting to which the vent structure is connected. That is, the air being discharged from an outlet vent or louver tends to have a non-uniform velocity profile (see FIG. 6). Thus, there is a need for a vent structure that is configured to minimize the introduction of turbulence and resulting airflow noise, while providing a more uniform velocity profile of exiting air.
The present invention provides a vent structure for an HVAC system. In general, the vent structure comprises an inlet-connector section, an outlet section, and a transition section between the inlet-connector section and outlet section. The inlet-connector section is at an inlet end of the vent structure and is adapted for connection with an inlet duct from which the vent structure receives a flow of air. The outlet section is at an outlet end of the vent structure and includes an outlet slot that is adapted to direct the flow of air into a room. The transition section has a flared portion that diverges in cross-sectional area as it extends generally toward the outlet section. The transition section has a constricted portion located between the inlet-connector section and the outlet slot. The constricted portion is also located substantially centrally within a plane that is generally perpendicular to a direction of air flow. The constricted portion is adapted to restrict the flow of air through a central portion of the transition section, thereby restricting the flow of air exiting a corresponding central portion of the outlet slot.
In another aspect of the invention, a vent structure comprises an inlet-connector section, an outlet section, and a transition section. The inlet-connector section is substantially as described above. The outlet section is at an outlet end of the vent structure and includes a generally rectangular outlet slot adapted to direct the flow of air into a room. The outlet slot is defined by left and right end margins and generally parallel upper and lower margins. The upper and lower margins of the slot are longer in dimension than the left and right end margins, such that a width of the outlet slot is greater than a height of the outlet slot. The transition section is located between the inlet-connector section and the outlet section. The transition section has a flared portion that is defined by generally parallel upper and lower walls and left and ride side portions. The left and right side portions of the flared portion are angled relative to one another such that the flared portion diverges in width as it extends toward the outlet section. The upper and lower walls of the flared portion of the transition section are contoured in a manner to define a constricted portion of the transition section. The constricted portion is located generally centrally between the left and right side portions of the flared portion for restricting the flow of air through the constricted portion, and thereby restricting the flow of air exiting a corresponding generally central portion of the outlet slot.
In still another aspect of the invention, a vent structure includes an inlet-connector section, an outlet section, and a transition section, which provides fluid communication between the inlet-connector section and outlet section. The inlet-connector section and outlet section are substantially as described above. The transition section has a flared portion defined by upper and lower walls and left and right side portions. The left and right side portions are angled relative to one another such that the flared portion diverges in width as it extends toward the outlet section. At least one of the upper and lower walls of the flared portion has a protrusion that extends generally toward the other of the upper and lower walls. The protrusion extends in a manner to restrict a part of the flow of air through the flared portion, thereby restricting a corresponding part of the flow of air exiting the outlet slot.
Further objects, features, and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings.